The CAS Registry Mumber 8043-27-4 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 8,0,4 and 3 respectively; the second part has 2 digits, 2 and 7 respectively. Calculate Digit Verification of CAS Registry Number 8043-27: (6*8)+(5*0)+(4*4)+(3*3)+(2*2)+(1*7)=84 84 % 10 = 4 So 8043-27-4 is a valid CAS Registry Number.